Implement retaining devices for power operated percussive tools



Dern 24, l`1957 G. l. EKSTRM IMPLEMENT RETAINING DEVICES FOR POWER v fOPERATED PERCUSSIVE TOOLS Filed April 12, 1955 2 Sheets-Sheet 1 Fig./

Fig. 3

j ATTORNY Dec. 24, 1957 G. l. EKsTRM 2,817,316 IMPLEMENT RETAININGnEvIcEs FOR POWER oPERATED PERcussIvE IrooLs Filed April 12, 1955 2sheets-sheet z Fig. 5 y Fig.

ATTORNEY IlVlPLEMENT RETAINING DEVICES FOR POWER OPERATED PERCUSSIVETOOLS Gsta Ivar Ekstrm, Nacka, Sweden, assignor to. Atlas CopcoAktiebolag, Nacka, Sweden, a corporation of Sweden Application April 12,1955, Serial No. 500,906

7 Claims. (Cl. 121-32) This invention relates to implement retainers forpercussive tools, and more particularly to implement retaining devicesfor preventing a working implement from becoming accidentally detachedfrom the tool in which it is supported or from being ejected therefromduring operation. One object of the invention is to provide improvedmeans for taking up the shocks to which a retainer for a collaredworking implement, such as a drill steel of a rock drill, a pick or aconcrete breaker or other similar tool is subjected. Another object ofthe invention is to provide improved means for positively holding theretainer for the implement in retaining as well as lin releasingposition, respectively. A still further object of the invention is toprovide an implement retaining device which may be assembled anddisassembled without the use of tools which may not be available when itis desired to take the device apart or to assemble the device. A stillfurther object of the invention is to provide a device in which allparts are positively locked against involuntary disassembly when thepower tool is in operation. Arrother object of the invention is toprovide a device which is simple in construction and inexpensive tomanufacture and in which the parts subjected to wear or damage mayeasily be replaced.

Other objects and features of the invention will be d-isclosed by thefollowing description and the appended claims.

In the accompanying drawings two embodiments of power operatedpercussive tools provided with implement retaining devices according tothe invention are illustrated by way of example. Fig. 1 is an elevationand par-tial section of the front end of a power operated percussivetool, such as a concrete breaker, provided with an implement retainingdevice according to the invention. Fig. 2 is a side view and partiallongitudinal section of the tool according to Fig. 1. Fig. 3 is an endview looking against the front end of the tool in Figs. 1 and 2. Fig. 4is a detail section on line IV-IV in Fig. 1. Fig. 5 is an elevation andpartial section of the front end of a further tool according to theinvention. Fig. 6 is a side view and partial longitudinal section of thetool according to Fig. 5,

and Fig. 7 is an end view and partial section looking against o thefront end of the tool in Figs. 5 and 6.

Referring to Figs. 1 and 2, 1 designates a cylinder casing of aconventional concrete breaker and 2 indicates a front head of saidbreaker, the casing and the front head being kept together by the usualside bolts 3 and nuts 4. The front head 2 accommodates the usual bushing5 which is provided with a polygonal axially extending opening 6 inwhich a shank 7 of a breaker steel 8 having a collar 9 lits.

The front head 2 is provided with two lugs 10 bored to receive bushings11 forming abutment surfaces 12 at the front ends of the bushings. Twoside members such as bolts 13 are inserted in the bushings 11 said boltshaving shoulders 14 adapted to rest on the abutment surfaces 12. In theillustrated embodiment the bolts 13 are disposed parallel to the axialopening 6 in the bushing 5 but nat- States Patent L' iiiiCC urally ifdesired they may be arranged at a small angle to said opening. The bolts13 are screw threaded at 15 and screwed into nuts 16, and helicalsprings 17 are fitted around the bolts between the nuts 16 and the lugs10, said springs serving to take up shocks to which the implementretainer may be subjected in operation of the tool. The nuts 16 areprovided with a yliat side surface 19, Fig. 4, cooperating withcorresponding flats 20 on the front head to prevent the nuts fromturning as long as the nuts engage the surfaces 20, the nuts being freeto move axially from the illustrated position of Fig. 1 Vtowards thefront end of the tool.

The bolts 13 at their extreme front ends carry a transverse shaft 22provided with trunnions 23 at the ends of the shaft mounted to turn inopenings 24 in the bolts 13 which form bearings for the trunnions 23.

A latching member 25 is mounted between the bolts 13 to swing on theshaft 22. The latching member is provided with a lip 26 which may beengaged by the foot of the operator, for instance, for swinging thelatching member, and the latching member furthermore is provided with afork 27 adapted to engage the collar 9 of the steel 8 when the latchingmember is in implement retaining position, as illustrated in Fig. 2.When the latching member is in implement releasing position, asindicated in chain dotted lines in Fig. 2 the fork 27 .is swung freefrom the path of the collar 9 so that the steel 3 may be removed fromthe breaker. The latching member has a transverse opening 28 of ovalcross section which in the lower part accommodates an intermediateportion of the transverse 'shaft 22. Said portion has a recessed flat 29which is engaged by a corresponding flat 30 on a shoe 31 inserted in theopening 28. The shoe 31 is provided with two end walls 32 and a body 33of yieldable material, such as soft rubber, is provided in the opening2S between .the back of the shoe 31 and the rear wall of the opening 28and between the end walls 32, said body being slightly compressed toforce the flat 30 of the shoe against the flat 29 of the transverseshaft. The shaft and the shoe are chamfered as indicated at 34 to permiteasy removal and insertion of the shaft.

In assembling the retaining device the bolts 13 are rst inserted in thebushings 11 and fitted with the springs 17 and then the bolts arescrewed into the nuts 16 so that the correct tension of the springs 17is obtained. The body 33 and the shoe 31 are then inserted in theopening 23 in the latching member whereupon the latching member isinserted between the bolts 13 in the position illustrated in Fig. 2. Theshaft 22 is then pushed through the opening 24 of one of the bolts 13into the opening 28 in the latching member and into the opening 24 ofthe other bolt in such a position that the shoe 31 will engage the at 29of the shaft as soon as the shaft has been moved completely into theposition illustrated in Fig. l. It is obvious that these assemblyoperations may be carried out without tools or with the aid of, forinstance, a hammer only.

The latching member 25 has cam surfaces 35 adapted to cooperate with camsurfaces 36 on the bolts 13 in order to hold the member in implementretaining position, as illustrated in full lines in Figs. 1 and 2, or inimplement releasing position, as illustrated in chain dotted lines inFig. 2. It is obvious that the point of contact between the cam surfaces35 and 36 is so remote from the axis of the shaft 22 that thespringiness of the rubber body 33 will be sutiicient to hold thelatching member in position and that the operability of the coaction ofthe cam surfaces 35 and 36 is not much etected by wear so that anettcient and safe holding of the latching member in both positions isguaranteed for a long time. It is also obvious that the shocks receivedby the latching member from the collar 9 in operation of the tool aretransmitted by the latching member to the springs 17 which may be ofhigh grade material. It is observed that a short travel of the latchingmember will compress the body 33 so that the latching member contactsthe rear face of the walls 32 and through them transmits the shock tothe bolts 13.

The tool illustrated in Figs. 5-7 is of the same type and general designas the tool illustrated in Figs. 1-4. Equivalent parts have thereforbeen designated with the same reference numerals and are not describedagain. The difference concerns mainly the side members which carry thetransverse shaft 22 for the latching member 25. In Figs. 5-7 the sidemembers are provided with openings 24 as above described for mountingthe trunnions 23 at the ends of the transverse shaft 22. However, therear ends of the side members are formed with a bolt portion 41 having ahead 42 at the rear end integral with the bolt portion, and a shoulderat 43. The bolt portion 41 has a reduced diameter in one direction, asobvious from Fig. 7 to enable the bolt portions to be inserted inopenings 44 in lugs 45 on the front head 2. A gap 46 extends over thefull axial length of the lugs so that the bolts may be inserted in theopenings 44 through said gaps after turning 90 relative to the positionof Fig. 7. Washers 47 are provided at the forward end of the lugs andthe shoulders 43 of the side members 40 rest on said washers, which alsoform the cam surfaces 36 with which the corresponding cam surfaces 35 ofthe latching member cooperate.

The opening 28 in the latching member is in this case axially longerthan in the embodiment of Figs. l-4 to accommodate a large rubber body48 which is disposed between the shoe 31 and the rear wall of theopening 28. The body 48 has recesses at 49 and 50 to permit the body tobe compressed axially without being jammed in the opening 28 when thebody takes up the shocks from the collar 9 on the fork 27 of thelatching member 25.

Various modifications of the implement retaining devices according tothe invention above described may be made within the scope of the claimswithout departing from the present invention.

What I claim is:

l. In a power operated percussive tool having a front head provided withan axially extending opening for receiving a shank of a workingimplement, two side members carried by said front head to move forwardrelative to the head substantially parallel to said axial opening,spring means arranged to counteract said forward movement, a transverseshaft carried by said side members, a latching member mounted on anintermediate portion of said shaft between the side members to swingfrom an implement retaining position to an implement releasing positionand vice versa, a transverse opening in said latching memberaccommodating said intermediate portion of the shaft, means in saidopening for yieldably retaining the intermediate portion in the opening,and means for retaining the latching member in implement retainingposition and in implement releasing position, respectively.

2. An implement retaining device according to claim l in which said sidemembers are formed as bolts, two lugs on said front head provided withguide openings for said bolts for guiding the bolts in said movementsubstantially parallel to the axial opening in the front head, abutmentsurfaces at the front end of said guide openings, shoulders on the boltsfor engaging said abutment surfaces, springs encircling the bolts at theopposite side of the lugs to said shoulders, and nuts screw threaded onthe bolts to retain said springs and compress the springs between thenuts and the lugs.

3. An implement retaining device according to claim 2, in which anon-circular guide surface is provided on each one of said nuts, acorresponding guide surface on the front head, said surfaces being soarranged as to prevent turning of the nuts when the surfaces are inengagement but to permit axial movement of the nuts forward of the toolfrom a position in which said shoulders of the bolts engage saidabutments on the lugs and against the pressure of the springs.

4. An implement retaining device according to claim l, in Which a firstcam surface is provided on said side members, a second cam surface onsaid latching member actuated to cooperate with said first cam surfaceby said spring means to retain the latching member in implementretaining position or in implement releasing position, respectively,said cam surfaces riding one over the other upon swinging of thelatching member from one of said positions to the other and capable ofpassing each other only upon displacement of the latching memberrelative to the side member and simultaneous compression of saidyieldable member.

5. In a power operated percussive tool having a front head provided withan axially extending opening for rcceiving a shank of a workingimplement, two side members carried by said front head and extendingsubstantially parallel to said axial opening, a latching member mountedbetween said side members to swing relatively to the side members froman implement retaining position to an implement releasing position andvice versa, a transverse opening in said latching member, a transverseshaft carried by said side members and extending through said transverseopening, a shoe engaging said shaft in thc opening, a yieldable memberin the opening forcing said shoe towards said shaft, a first cam surfacein fixed position on said front head, a second cam surface on saidlatching member cooperating with said first cam surface to retain thelatching member in implement retaining position or in implementreleasing position, respectively, said cam surfaces riding one over theother upon swinging of the latching member from one of said positions tothe other and capable of passing each other only upon displacement ofthe latching member relative to the side member and simultaneouscompression of said yieldable member.

6. In a power operated percussive tool having a front head provided withan axially extending opening for receiving a shank of a Workingimplement, two side members carried by said front head, two lugs on thefront head provided with openings in which said side members are fitted,a latching member mounted between said side members to swing relativelyto the side members from an implement retaining position to an implementreleasing position and vice versa, a transverse oval opening in saidlatching member, a transverse shaft mounted to turn in said side membersand having an intermediate portion extending through the front portionof said oval opening. a reduced portion on said intermediate portion ofsaid transverse shaft, a shoe in the oval opening fitting said reducedportion to retain the transverse shaft in the latching member, ayieldable member in the rear portion of the oval opening forcing saidshoe toward the transverse shaft. a first cam surface in fixed positionon said front head, a second cam surface on said latching membercooperating with said first cam surface to retain the latching member inimplement retaining position or in implement releasing position,respectively, said cam surfaces riding on over the other upon swingingof the latching member from one of said positions to the other andcapable of passing each other only upon displacement of the latchingmember relative to the side member and simultaneous compression of saidyieldable member.

7. An implement retaining device according to claim 6, in which the sidemembers have a rear portion formed as bolt with a head at the rear endand a shoulder at the front end, and in which the openings in the lugsare substantially cylindrical extending substantially parallel to theopening in the front head, a longitudinal gap in the lugs merging intosaid openings in the lugs and formed to permit insertion of the boltssideways through said gaps into the openings in the lugs, said boltshaving a reduced diameter in one direction permitting such insertion ofthe bolts and locking of the bolts upon turning a suit- 5 able angle inthe yopenings in the lugs, and said head and shoulder on the boltslocking them in .axial direction.

References Cited in the le of this patent UNITED STATES PATENTS HoskinOct. 30, 1923 Renfer Oct. 24, 1933 Smith, et a1 Jan. 1, 1935 Curtis Jan.28, 1941 Lear Mar. 7, 1950

